It hit at 3.17am local time (4.47am AEDT).
As well as Indonesia and Australia, the quake has also hit East Timor.
It was reportedly felt as far south as Tennant Creek and the southern Kimberly region of Western Australia.
The Bureau of Meteorology has said there is no tsunami threat for Australia. However, Indonesian authorities have issued a tsunami alert for the Tanimbar islands.
Nonetheless, residents of Darwin reported feeling the quake early on Tuesday morning.
“That was the (most) intense earthquake I’ve ever felt since being in Darwin.,” said one on social media.
NT News reporter Annabel Bowles posted a video from her apartment when the quake was progressing, with the sound of the tremor clearly audible.
Channel 9′s Darwin chief of staff Kathleen Gazzola said it was the “strongest I’ve ever felt my entire life in Darwin”.
Northern Territory Police, Fire and Emergency Services posted on Facebook asking if everyone was okay and provided advice on what to do after an earthquake.
Residents responded, saying the frightening quake was the biggest they had felt in many years.
“Did anyone else hear the roar? First time I’ve heard it during one,” one man from Darwin wrote.
“The strongest earthquake I have felt in Darwin. My high set house in Rapid Creek shuddered, the floor shook and furniture moved. It was pretty scary,” another Darwin resident said.
“Heard door rattling, jumped out of bed, ran to fish tank to stop it swaying. Went for a long time, strongest I have felt since the big one that hit Newcastle NSW in the 80s,” a woman added.
Those in apartments felt it even worse.
“Was an experience 30 levels up here in the CBD and not a fun one,” one woman said.
“On the 4th floor of a motel in Darwin city, and yeah that quake freaked me out by how long it lasted,” said another.
“We’re on 6 (floor) and it was so scary!!!” wrote a third.
Some people said they felt movement for about five minutes.
